1. Field of Invention
The invention relates to new benzoindole styryl compounds and, in particular, to new benzoindole styryl compounds and their uses in high-density optical recording media.
2. Related Art
With the coming of information and multimedia era, computer, communication and consumer electronics have higher demands for larger storage density and capacity. Due to the large amount of information exchange, it is desirable to develop a high-density, small and cheap storage medium. Conventional magnetic storage media are already insufficient for current uses; high-density optical information storage media are the main subject under study. There had been some proposed principles and methods for increasing the storage density in optical information storage media. Some of them are important and have already been successfully implemented. One method is to shorten the wavelength of the laser beam. For example, red lasers are replaced by blue lasers. One can also achieve the same goal by increasing the NA (Numerical Aperture) of the lens. Another method is to improve the digital signal coding means or to utilize optical disk recording with the so-called ultra-high resolution near-field optical structure. These methods can all effectively increase the storage density.
On the other hand, another research field of optical information storage media is to replace the organic dyes used in optical recording layers by those with better optical properties. In recent years, one-time recording compact discs (CD-R) have become people's favorite storage media due to their cheap prices, fast burning speeds, convenience in carriage, and high compatibility among different personal computers. To achieve high-density storage, dyes for such media as one-time recording digital versatile discs (DVD-R) with 4.7 GB capacity have become an important subject under research. Since the laser for high-density storage media such as DVD-R's has a light wavelength of 650 nm, which is different from that of the laser for CD-R's (780 nm), the dyes cannot be shared between the two kinds of media. This is why developing new organic dyes for high-density storage media is an urgent need.